Stock Plans - Additional Information (Detail) (USD $)	12 Months Ended									0 Months Ended	1 Months Ended	12 Months Ended			12 Months Ended		12 Months Ended			0 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2013 Restricted stock	Sep. 30, 2012 Restricted stock	Sep. 30, 2011 Restricted stock	Sep. 30, 2013 Restricted stock Maximum	Sep. 30, 2013 Restricted stock Senior Management	Sep. 30, 2012 Restricted stock Senior Management	Feb. 08, 2012 Employee Stock Purchase Plan, 1995 Plan	Feb. 29, 1996 Employee Stock Purchase Plan, 1995 Plan	Sep. 30, 2013 Employee Stock Purchase Plan, 1995 Plan	Feb. 12, 1996 Employee Stock Purchase Plan, 1995 Plan Before Amendment	Feb. 08, 2012 Employee Stock Purchase Plan, 1995 Plan After Amendment Maximum	Sep. 30, 2013 1998 Employee Equity Incentive Plan Stock options	Sep. 30, 2013 Equity Incentive Plan 2000	Sep. 30, 2013 Equity Incentive Plan 2000 Restricted stock	Sep. 30, 2013 Equity Incentive Plan 2000 Restricted stock Senior Management	Sep. 30, 2013 Equity Incentive Plan 2000 Restricted stock Share Vesting Over Three Year Period	Oct. 26, 2005 Helix Stock Options	Sep. 30, 2013 Helix Stock Options
Equity Incentive Plan [Line Items]
Equity incentive plan, vesting period							4 years								4 years		3 years
Equity incentive plan, expiration Period															7 years
Shares of common stock reserved for issuance																9,000,000
Options outstanding	15,540	193,182														0				689,622	15,540
Shares available for grant	3,259,558															2,792,393					467,165
Restricted stock or units issued net of cancellations																	392,931
Awards granted				1,471,977				1,394,000	1,527,000									562,125
Restricted stock or units vesting description																	These restricted stock awards generally have the following vesting schedules: immediate; three year vesting in which one-third vest at the end of Year 1, one-third vest at the end of Year 2 and one-third vest at the end of Year 3
Equity incentive plan vesting in year one, percentage																	33.33%
Equity incentive plan vesting in year two, percentage																	33.33%		50.00%
Equity incentive plan vesting in year three, percentage																	33.34%		50.00%
Options to purchase Helix common stock																				765,480
Closing stock price	$ 9.31
Total intrinsic value of options exercised	$ 19,000	$ 56,000	$ 15,000
Cash received from employee stock option exercises	67,000	103,000	6,000
Weighted average grant date fair value, Awards granted				$ 9.33	$ 11.80	$ 11.27
Fair value of restricted stock awards vested				7,300,000	5,600,000	7,400,000
Unrecognized compensation cost				$ 5,600,000
Unrecognized compensation cost, estimated weighted average amortization period				1 year 6 months
Additional shares of common stock available for purchase										1,000,000
Shares of common stock available for purchase												865,926	3,000,000	4,000,000
Employee stock purchase plan, offering period											6 months
Employee stock purchase plan, price per share percentage											85.00%
Maximum percentage of base pay withheld and applied toward the purchase of shares										10.00%
Stock purchase under employee stock purchase plan												3,134,074